Input device and method of manufacturing the same

ABSTRACT

A touch panel includes a transparent panel, a decorative layer which is formed in a decorative region on a first surface of the transparent panel, a transparent electrode which is formed from a transparent input region of the first surface to a surface of the decorative layer, and a wiring layer which is formed to extend to the surface of the decorative layer and electrically connected to the transparent electrode.

CLAIM OF PRIORITY

This application claims benefit of Japanese Patent Application No.2011-072496 filed on Mar. 29, 2011, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an input device (touch panel which isused in combination with a liquid crystal display or the like, and amethod of manufacturing the same.

2. Description of the Related Art

As described in Japanese Unexamined Patent Application Publication No.2009-301767, a touch panel includes a transparent surface panel(transparent substrate 23), a decorative layer (light-shielding layer24) which is formed in a decorative region below the surface panel, atransparent planarizing layer (overcoat layer 25) which is formed overthe entire region of the lower surfaces of the surface panel and thedecorative layer, and transparent electrodes (transparent conductivelayer 26) which are formed in the lower surface of the planarizinglayer, and the like.

In Japanese Unexamined Patent Application Publication No. 2009-301767,transparent resin, such as photosensitive acrylic resin is spin-coatedto form the planarizing layer.

However, in the configuration in which the planarizing layer is formedof a resin layer by spin coating, in particular, the degree ofplanarization of the planarizing layer is degraded due to a step betweenthe surface panel and the decorative layer, or the like. For thisreason, there is a problem in that the transparent electrodes may not beformed on the planarized surface, causing deterioration in sensorsensitivity.

In Japanese Unexamined Patent Application Publication No. 2009-301767,since a planarizing layer is necessary, the touch panel increases inthickness, and there is a problem in that it is difficult toappropriately achieve a reduction in thickness.

A process for manufacturing a touch panel of the related art includesprinting of a decorative layer printing, deposition of transparentelectrodes, such as ITO (Indium Tin Oxide), pattern formation byphotolithography, and bonding of base materials. In this way, aplurality of complex manufacturing process techniques are required,leading to an increase in instrument investment cost or processtechnique development cost. Accordingly, the manufacturing process isextended, causing deterioration in productivity.

In a touch panel described in Japanese Unexamined Patent ApplicationPublication No. 2009-193587, a decorative layer (mask layer 12), aplanarizing layer (smoothing layer 15), and transparent electrodes(sensing circuit 13) are laminated in a decorative region below asurface panel (single substrate 11). Accordingly, there are the sameproblems as those in Japanese Unexamined Patent Application PublicationNo. 2009-301767.

SUMMARY OF THE INVENTION

The present invention provides a thin input device having satisfactorysensor sensitivity.

The present invention also provides a method of manufacturing an inputdevice based mainly on a printing process.

An input device according to an aspect of the invention includes atransparent base material, a decorative layer which is formed in adecorative region on a first surface of the transparent base material, atransparent electrode which is formed from a transparent input region ofthe first surface to a surface of the decorative layer, and a wiringlayer which is formed to extend to the surface of the decorative layerand electrically connected to the transparent electrode.

According to the aspect of the invention, both the decorative layer andthe transparent electrode are formed on the same first surface of thetransparent base material. At this time, according to the aspect of theinvention, the transparent electrode is formed from the transparentinput region of the first surface to the surface of the decorativelayer, and the wiring layer which is electrically connected to thetransparent electrode are formed on the surface of the decorative layer.Accordingly, there is no case where the wiring layer appears in thetransparent input region, such that electrical connection between thewiring layer and the transparent electrode in the decorative region canbe stabilized. The transparent electrode is formed to the surface of thedecorative layer 3, such that a portion of the decorative region canalso be used as the input region, thereby extending the input region.

According to the aspect of the invention, since the transparentelectrode is formed on the same flat first surface as the decorativelayer, the transparent electrode can be formed on the planarized surfacecompared to a case where the transparent electrode is formed on thesurface of the planarized layer by spin coating or the like, therebyobtaining excellent sensor sensitivity. Unlike the related art, since itis not necessary to form the planarizing layer, it is possible torealize reduction in thickness compared to the related art.

The decorative layer, the transparent electrode, and the wiring layermay be printed.

A protective layer may be provided on the first surface to cover thesurface of the transparent electrode and the wiring layer. Therefore, itis possible to appropriately protect the transparent electrode and thewiring layer.

A lateral surface of the decorative layer which defines the boundarybetween the transparent input region and the decorative region may be aninclined surface which is inclined in a direction away from thetransparent input region, and the transparent electrode may be formedfrom the transparent input region of the first surface to the inclinedsurface. Therefore, it is possible to form the transparent electrodefrom the transparent input region of the first surface to the surface ofthe decorative layer simply and stably.

The transparent base material may be a transparent panel whose secondsurface opposite to the first surface is an operating surface.Therefore, it is possible to more effectively realize reduction inthickness of the input device.

The transparent electrodes may have a single-layer structure. Therefore,it is possible to more effectively realize reduction in thickness of theinput device.

A method of manufacturing an input device according to another aspect ofthe invention includes the steps of printing a decorative layer in adecorative region on a first surface of a transparent base material,printing a transparent electrode from a transparent input region of thefirst surface to a surface of the decorative layer, and printing awiring layer electrically connected to the transparent electrode on thesurface of the decorative layer.

According to the aspects of the invention, since the main process forforming the decorative layer, the transparent electrode, and the wiringlayer is performed using printing, unlike the related art, a pluralityof process techniques are not required, thereby suppressing instrumentinvestment cost or manufacturing process time and improvingproductivity.

The method may further include the step of, after printing the wiringlayer, forming a protective layer on the first surface to cover thesurface of the transparent electrode and the wiring layer. Thetransparent electrodes may be formed on the first surface with asingle-layer structure.

With the input device according to the aspect of the invention, sincethe transparent electrode is formed on the same flat first surface asthe decorative layer, the transparent electrode can be formed on theplanarized surface compared to a case where the transparent electrode isformed on the surface of the planarizing layer by spin coating or thelike, thereby obtaining excellent sensor sensitivity. Unlike the relatedart, since it is not necessary to form the planarizing layer, it ispossible to realize reduction in thickness compared to the related art.

With the method of manufacturing an input device according to anotheraspect of the invention, since the main process for forming thedecorative layer, the transparent electrode, and the wiring layer isperformed using printing, unlike the related art, a plurality of processtechniques are not required, thereby suppressing instrument investmentcost or manufacturing process time and improving productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a capacitance type touch panel (input device)in this embodiment.

FIG. 2 is a longitudinal sectional view of the touch panel shown in FIG.1 when taken along the line A-A and viewed in the direction of thearrow.

FIG. 3 is a partial enlarged longitudinal sectional view of a touchpanel in another embodiment different from FIG. 2.

FIG. 4 is a partial enlarged longitudinal sectional view of a touchpanel in another embodiment different from FIG. 2.

FIGS. 5A to 5D are process views (longitudinal sectional views) showinga method of manufacturing a touch panel in this embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a plan view of a capacitance type touch panel (input device)in this embodiment. FIG. 2 is a longitudinal sectional view of the touchpanel shown in FIG. 1 when taken along the line A-A and viewed in thedirection of the arrow (an operating surface 9 turns downward).

A touch panel 1 of this embodiment has a transparent panel 5 in asurface layer, a decorative layer 3, transparent electrodes 4, wiringlayers 6, a protective layer 21, and the like.

The terms “transparent” and “transmission property” used herein refersto a state where visible light transmittance is equal to or greater than60% (preferably, equal to or greater than 80%). It is preferable thatthe haze value is equal to or smaller than 6.

FIG. 2 which is a longitudinal sectional view of FIG. 1 shows a statewhere the transparent panel 5 in the layer is on the lower side.Accordingly, in FIG. 2, the lower surface of the transparent panel 5 isan operating surface 9.

The transparent panel 5 is formed of glass, transparent plastic, or thelike, and the material is not particularly limited. The transparentpanel 5 may have a flat shape as a whole or may be a housing shape.

As shown in FIG. 2, the colored decorative layer 3 is formed in adecorative region 1 b on a first surface (a rear surface opposite to theoperating surface 9) 5 a of the transparent panel 5. The decorativeregion 1 b is provided in a shape surrounding the periphery of atransparent input region 1 a. Although the decorative layer 3 is formedby, for example, screen printing, the printing method is notparticularly limited. The decorative region 1 b in which the decorativelayer 3 is formed is non-transmissive, and the transparent input region1 a is transmissive. Although any material can be used for thedecorative layer 3, when the decorative layer 3 is conductive, it isnecessary to form an insulating layer to overlap the entire surface 3 aof the decorative layer 3. Although the insulating layer isnon-transmissive or transmissive, when the insulating layer spreads outof the lateral surface of the decorative layer 3 into the transparentinput region 1 a, the insulating layer is transparent.

As shown in FIG. 2, the transparent electrodes 4 are formed from thetransparent input region 1 a on the first surface 5 a of the transparentpanel 5 to the surface 3 a of the decorative layer 3. The term “thesurface 3 a of the decorative layer 3” used herein refers to a surfacewhich corresponds to the rear surface of the touch panel 1 when viewedfrom the operating surface 9 or corresponds to the lower surface if theoperating surface 9 turns toward the upper surface. As shown in FIG. 1,the transparent input region 1 a is provided over the wide range at thecenter of the touch panel 1. In this embodiment, the transparent inputregion 1 a has, but is not limited to, a rectangular shape.

As shown in FIG. 1, the transparent electrodes 4 each have a pair of afirst transparent electrode 4 a and a second transparent electrode 4 bseparately formed, and a plurality of sets are formed at an interval inthe Y direction. In this embodiment, although the shapes of the firsttransparent electrode 4 a and the second transparent electrode 4 b arenot limited, the first transparent electrode 4 a and the secondtransparent electrode 4 b are formed to change in width in the Ydirection gradationally or in a stepwise manner toward the X direction.

For the transparent electrodes 4, any materials may be used as long asthe material is printable, and the material is not particularly limited.For example, examples of a conductive material includePEDOT/PSS-containing conductive ink, Ag nanowire-containing conductiveink, and carbon nanotube-containing conductive ink. In regard to theprinting method, screen printing, ink jet printing, thermal transfer, orthe like may be used. The same is applied to the printing method of thedecorative layer 3 or the wiring layers 6.

As shown in FIG. 2, a lateral surface 3 b of the decorative layer 3which defines the boundary B between the transparent input region 1 aand the decorative region 1 b is an inclined surface (hereinafter,referred to as an inclined surface 3 b) which is inclined in a directionaway from the transparent input region 1 a. As shown in FIG. 2, thetransparent electrodes 4 are formed from the transparent input region 1a of the first surface 5 a to the inclined surface 3 b of the decorativelayer 3.

as shown in FIGS. 1 and 2, a plurality of wiring layers 6 are formed topartially overlap the transparent electrodes 4 and to extend to the flatsurface 3 a of the decorative layer 3. In this way, since the wiringlayers 6 are formed on the surface 3 a of the decorative layer 3, unlikeFIG. 1, the wiring layers 6 are not actually visible from the operatingsurface 9 of the touch panel 1 as shown in FIG. 1. Meanwhile, in FIG. 1,the wiring layers 6 are visible through the decorative layer 3. Thewiring layers 6 are formed by, for example, screen printing, and theprinting method is not particularly limited.

The wiring layers 6 are formed of a metal material, such as Ag, Cu, Cualloy, CuNi alloy, or Ni. For example, the wiring layers 6 are formed byprinting Ag paste.

The wiring layers 6 are wired in the surface 3 a of the decorative layer3 and, as shown in FIG. 1, are packed together in a portion which isconnected to a flexible printed board (not shown). The tips of thewiring layers 6 form an external connection portion 6 a which iselectrically connected to the flexible printed board (not shown).

As shown in FIG. 2, the protective layer 21 is provided on the firstsurface 5 a of the transparent panel 5 to cover the surfaces of thetransparent electrodes 4 and the wiring layers 6. The protective layer21 is a hard coat film (transparent protective layer) in which a hardcoat layer, such as urethane acrylate, is formed on the surface of athin PET base material. The protective layer 21 may be adhered to theexposed surfaces of the transparent electrodes 4 and the wiring layers 6through an optical transparent adhesive layer (OCA). Meanwhile, theprotective layer 21 does not cover the surface of the externalconnection portion 6 a, such that the external connection portion 6 acan be exposed and connected to the flexible printed board.

In the touch panel 1 shown in FIGS. 1 and 2, if the operator touches orapproaches the operating surface 9 of the transparent panel 5 in thesurface layer of the touch panel 1 with his/her finger, capacitancebetween the first transparent electrodes 4 a close to the finger and thesecond transparent electrodes 4 b close to the finger changes. Thus, itis possible to calculate the operating position of the finger on thebasis of the change in capacitance.

As shown in FIG. 3, a structure may be made in which a decorative layer3 and transparent electrodes 4 are formed on a first surface 18 a of atransparent base material 18, such as a PET film, and a transparentpanel 5 made of glass or transparent plastic is adhered to a secondsurface 18 b (a surface opposite to the first surface 18 a) of thetransparent base material 18 through an optical transparent adhesivelayer (OCA) 19. Meanwhile, as shown in FIG. 2, if the decorative layer 3and the transparent electrodes 4 are formed on the transparent panel 5in the surface layer, it is possible to reduce the number of componentsand to achieve reduction in thickness of the touch panel 1 andimprovement in sensor sensitivity.

In a touch panel shown in FIG. 4, a laminated structure is made in whichtwo layers of transparent electrodes 15 and 16 are laminated through atransparent insulating layer 17. At this time, for example, a pluralityof transparent electrodes 15 extend in the X direction at an interval inthe Y direction, and a plurality of transparent electrodes 16 extend inthe Y direction at an interval in the X direction.

As shown in FIG. 4, while transparent electrodes 15 are printed from thetransparent input region 1 a on the first surface 5 a of the transparentpanel 5 to the surface 3 a of the decorative layer 3, in regard totransparent electrodes 16, a transparent conductive material, such asITO (Indium Tin Oxide), may be film-formed on the surface of atransparent base material 23, such as a PET film, using sputtering ordeposition and patterned using a photolithography technique. Thetransparent base material 23 on which the transparent electrodes 16 areformed and the transparent panel 5 on which the transparent electrodes15 are formed may be adhered through an optical transparent adhesivelayer (OCA) (transparent insulating layer 17).

Meanwhile, in this embodiment, as shown in FIGS. 1 and 2, thetransparent electrodes 4 can have a single-layer structure, thus it ispossible to promote reduction in thickness of the touch panel 1.

FIGS. 5A to 5D are process views showing a method of manufacturing thetouch panel 1 of this embodiment.

In the step of FIG. 5A, the decorative layer 3 is printed in thedecorative region 1 b on the first surface 5 a of the transparent panel5 by screen printing or the like. While the first surface 5 a of thetransparent panel 5 is a flat surface, the operating surface 9 may notbe flat. The transparent panel 5 may form a portion of the housing.

Next, in the step of FIG. 5B, the transparent electrodes 4 are printedfrom the transparent input region 1 a on the first surface 5 a of thetransparent panel 5 to the inclined surface 3 b and the flat surface 3 aof the decorative layer 3 in the planar shape shown in FIG. 1 by screenprinting or the like.

At this time, since the lateral surface of the decorative layer 3 is theinclined surface 3 b, it is possible to form the transparent electrodes4 from the first surface 5 a to the surface 3 a of the decorative layer3 simply and stably.

Next, in the step of FIG. 5C, a plurality of wiring layers 6 whichoverlap the transparent electrodes 4 a and 4 b (see FIG. 1) in thethickness direction and extend to the surface 3 a of the decorativelayer 3 are printed by screen printing or the like.

In the step of FIG. 5D, the protective layer 21 is formed on the firstsurface 5 a of the transparent panel 5 to cover the exposed surfaces ofthe transparent electrodes 4 and the wiring layers 6. The protectivelayer 21 is, for example, a hard coat film (transparent protectivelayer) in which a hard coat layer, such as urethane acrylate, is formedon the surface of a thin PET base material. The protective layer 21 maybe adhered to the surfaces of the transparent electrodes 4 and thewiring layers 6 through an optical transparent adhesive layer (OCA).

In this embodiment, both the decorative layer 3 and the transparentelectrodes 4 are formed on the same first surface 5 a of the transparentpanel 5. At this time, in this embodiment, the transparent electrodes 4are formed from the transparent input region 1 a of the first surface 5a to the surface of the decorative layer 3, and the wiring layers 6which are electrically connected to the transparent electrodes 4 areformed on the surface of the decorative layer 3. Therefore, there is nocase where the wiring layers 6 appear in the transparent input region 1a, such that electrical connection between the wiring layers 6 and thetransparent electrodes 4 in the decorative region 1 b can be stabilized.The transparent electrodes are formed to the surface of the decorativelayer 3, such that a portion of the decorative region can also be usedas the input region, thereby extending the input region.

As described above, in this embodiment, since the transparent electrodes4 can be formed on the same flat first surface 5 a as the decorativelayer 3, the transparent electrodes can be formed on the planarizedsurface compared to a case where the transparent electrodes are formedon the surface of the planarizing layer by spin coating or the like,thereby obtaining excellent sensor sensitivity. Unlike the related art,since it is not necessary to form the planarizing layer, it is possibleto realize reduction in thickness compared to the related art.

In the method of manufacturing the touch panel 1 of this embodiment,since the main process for forming the decorative layer 3, thetransparent electrodes 4, and the wiring layers 6 is performed usingprinting, unlike the related art, a plurality of process techniques arenot required, thereby suppressing instrument investment cost ormanufacturing process time and improving productivity.

The touch panel 1 of this embodiment is a capacitance type, and a liquidcrystal display (LCD) (not shown) is arranged on the rear side of thetouch panel 1 (the side opposite to the operating surface 9). Thedisplay form of the liquid crystal display can be viewed from thetransparent input region 1 a of the touch panel 1, and in thisembodiment, the operator can carry out an input operation while viewinga display form in the transparent input region 1 a.

The touch panel (input device) of this embodiment is used in mobilephones, digital cameras, PDAs, game machines, car navigation systems, orthe like.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims of the equivalents thereof.

1. An input device comprising: a transparent base material having afirst surface; a decorative layer formed on the first surface in adecorative region thereof; a transparent electrode formed on the firstsurface in a transparent input region thereof and extending onto asurface of the decorative layer; and a wiring layer formed onto thesurface of the decorative layer and electrically connected to thetransparent electrode.
 2. The input device according to claim 1, whereinthe decorative layer, the transparent electrode, and the wiring layerare printed layers.
 3. The input device according to claim 1, furthercomprising: a protective layer provided over the first surface to coverthe transparent electrode and the wiring layer.
 4. The input deviceaccording to claim 1, wherein an edge portion of the decorative layerwhich defines a boundary between the transparent input region and thedecorative region has an inclined side surface having an upward slope ina direction away from the transparent input region, and the transparentelectrode extends onto the inclined side surface.
 5. The input deviceaccording to claim 1, wherein the transparent base material is atransparent panel having an operating surface as a second surfaceopposite to the first surface.
 6. The input device according to claim 1,wherein the transparent electrode includes a plurality of electrodeshaving a single-layer structure.
 7. A method of manufacturing an inputdevice having a transparent base material, the method comprising:printing a decorative layer on a first surface of the transparent basematerial in a decorative region thereof; printing a transparentelectrode on the first surface in a transparent input region thereof,the transparent electrode extending onto a surface of the decorativelayer; and printing a wiring layer on the surface of the decorativelayer so as to be electrically connected to the transparent electrode.8. The method according to claim 7, further comprising: after printingthe wiring layer, forming a protective layer over the first surface tocover the transparent electrode and the wiring layer.
 9. The methodaccording to claim 7, wherein the transparent electrode includes aplurality of electrodes formed on the first surface with a single-layerstructure.
 10. The method according to claim 7, wherein the decorativelayer is printed such that an edge portion of the decorative layer whichdefines a boundary between the transparent input region and thedecorative region has an inclined side surface having an upward slope ina direction away from the transparent input region, and wherein thetransparent electrode is printed so as to extend onto the inclined sidesurface of the decorative layer.